Preformed pattern for producing occlusal splints

ABSTRACT

A preformed pattern for forming an occlusal splint comprises a U-shaped member composed of material that is form-stable at room temperature and sufficiently pliable at an elevated temperature to be conformed to the bits of a person&#39;s jaw or to a model of such person&#39;s jaw.

This invention relates to a preformed pattern for use in the productionof dental splints and to methods of forming such patterns.

BACKGROUND OF THE INVENTION

It is known to use occlusal splints for combatting bruxism andperiodontal problems, to relieve strain on the temporal mandibularjoint, and for other well-known purposes. The use of patterns in themanufacture of such splints is common and millions of such patterns areused every year. Heretofore, however, the production of such patternshas been a tedious, manual operation requiring the services of a dentalprofessional or a highly skilled dental technician.

In general, one procedure currently in use for the production of asplint pattern involves the formation of plaster models of a patient'smaxillary and mandibular jaw teeth, placing the models in anarticulator, heating a quantity of dental wax to make it manuallypliable, and thereafter shaping the pliable wax to form an arcuateapproximation of the patient's bite. While still pliable the arcuatemember is inserted between the maxillary and mandibular jaw teeth modelsand conformed as much as possible to the configuration of the patient'steeth, following which an impression is made of the patient's bite inthe still pliable arcuate member so as to form a pattern whichsubsequently may be used in the production of the splint.

Another current method for forming a splint pattern correspondssubstantially to that described above except that the pattern is formeddirectly in the patient's mouth without the use of models or anarticulator.

The manner of forming patterns as described above has many disadvantagesother than the time expended in the production. For example, the labialand buccal length and wall thickness rarely, if ever, are uniform. Inaddition, those patterns which are used for the production of splintshaving cuspid risers must have excess wax applied manually, a procedurewhich leaves a great deal to be desired in terms of location, thickness,height, and slope. Further, the manual formation of a splint patternfrom maxillary and mandibular models presents problems in effectingprecise orientation of the pattern in the patient's mouth.

A splint pattern formed in accordance with the present inventionovercomes or greatly minimizes all of the foregoing objections.

SUMMARY OF THE INVENTION

A pattern formed in accordance with the invention comprises asubstantially U-shaped member having spaced apart limbs converging in adirection toward one end of such member and being joined atcorresponding ends by an arcuate bight. The member has a relatively flatbase from one surface of which spaced apart inner and outer side wallsextend in the same direction. The opposite surface of the base isrelatively flat except for a pair of upstanding protrusions spaced fromone another along the arc of the bight. Each protrusion has its maximumheight substantially in the plane of the adjacent side wall and declinessmoothly and substantially uniformly toward the otherwise flat surface.If the splint is adapted to be applied to the maxillary jaw, theprotrusions are located at the labial or outer side wall, whereas if thesplint is adapted to be fitted to the mandibular jaw, the protrusionsare located at the lingual or inner side wall. At the midpoint of thebight the labial side wall is provided with a forwardly extending ridgeor projection which preferably extends the full height of the wall.

The protrusions provided on the otherwise flat surface of the patternare for the purpose of enabling the finished splint to have cuspidrisers at the proper locations. The forwardly projecting ridge isprovided to facilitate proper orientation of the pattern in the moldedarticulator or the patient's mouth.

The pattern is formed by a molding process wherein dental wax or othersuitable material, form-stable at room temperature and flowable atelevated temperatures, is placed in a mold and subjected to sufficientpressure to enable the base and side walls of the pattern to be formedto the proper configuration and wall thickness. The material of thepattern is preferably sufficiently flowable when heated a few degreesabove normal human body temperature to enable an occlusion to be formedin the limbs. The molded part is removed from the mold and trimmed toform the pattern. The pattern will have the cuspid risers and thelocating ridge as integral parts thereof. Patterns thus formed then maybe delivered to dentists and/or dental technicians who will be able touse them in the conventional manner for the production of dentalsplints.

THE DRAWINGS

Methods and apparatus according to the invention are disclosed in thefollowing description and in the accompanying drawings, wherein:

FIG. 1 is a flow chart illustrating the steps involved in the productionof a finished pattern;

FIG. 2 is a flow chart illustrating the steps involved in making afinished splint from a pattern;

FIG. 3 is a top plan view of one half of a mold for making a pattern;

FIG. 4 is a bottom plan view of the other half of the mold;

FIG. 5 is a top plan view of the finished pattern;

FIG. 6 is a bottom plan view of the pattern;

FIG. 7 is a front elevational view of the pattern; and

FIG. 8 is a sectional view taken on line 8--8 of FIG. 5.

DETAILED DESCRIPTION

A splint pattern constructed in accordance with the invention isdesignated generally by the reference character 1 in FIGS. 6-8 andcomprises a generally U-shaped member 2 having spaced apart limbs 3 and4 converging in a direction toward one end of the member and beingjoined at corresponding ends by an arcuate bight 5. The member 2 has abase 6 from the inner surface of which spaced apart, upstanding sidewalls 8 and 9 extend in the same direction.

The opposite, outer surface 10 of the base 6 is substantially flat andsmooth except for a pair of protrusions 11 spaced along the arc of thebight 5. In the disclosed embodiment, the protrusions 11 are located atpositions corresponding to those of a person's cuspids and eachprotrusion has its point of maximum height substantially coplanar orflush with the adjacent outer wall 8 and slopes or declines uniformlyfrom such point toward the surface 10. The maximum height of eachprotrusion above the surface 10 is between about 2 and 3 mm.

At the midpoint of the bight 5 is a protruding ridge 12 which preferablyextends the full height of the outer wall and has a height of betweenabout 1 and 1.5 mm. The width of the ridge preferably does not exceedabout 1 mm.

The base 6 of the member 2 is of substantially uniform thickness exceptfor the protrusions 11. The outer wall 8 is of substantially uniformthickness except for the ridge 12. The thickness of the inner wall 9 issubstantially uniform, and the thickness of each wall correspondssubstantially to the thickness of the other walls, except for theprotrusions 11 and the ridge 12. The inner side wall 9 forms an obtuseincluded angle of substantially 110°-130° with the base 6.

The base 6 intentionally has a width greater than that of a person'steeth. This ensures that the pattern may be used for the production ofsplints for persons whose bites are considerably different.

A pattern according to the invention may be formed in a number ofdifferent ways. Preferably, however, the pattern is formed by a moldingprocess wherein a moldable material that is form-stable at roomtemperature, such as dental wax, is heated to a temperature at which itbecomes flowable or pliable following which it is inserted in a mold andsubjected to pressure to conform the material to the configuration ofthe mold cavity. The molded material is cooled, following which it isremoved from the mold and trimmed to form the finished pattern.

One form of mold for producing the pattern is shown in FIGS. 3-4 ascomprising a mandibular mold half 15 having a flask 16 filled with astone material 17 in which is formed a protruding, arcuate die 18. Alongthe base of the outer surface of the die 18 is a groove 19, the purposeof which is to form a well defined free edge for the outer wall 8 of thepattern.

The mold half 15 cooperates with a maxillary mold half 20 having a flask21 also filled with stone material 22 and in which is a cavity 23 ofsuch size and configuration as to accommodate the die 18. The flask 21has locating pins 24 adapted for removable accommodation in openings 25provided in the flask 16 to enable the die 18 to be located properlywithin the cavity 23. The relative sizes of the die 18 and the cavity23, of course, are such as to provide adequate space between theirconfronting surfaces to enable the formation therebetween of the baseand side walls of the pattern. In addition, the cavity 23 hasdepressions 26 and 27 for the formation of the protrusions 11 and theridge 12, respectively.

The mold disclosed in FIGS. 3-4 is a manually operable mold. In the useof such mold, the two halves are separated, following which a sheet ofdental wax or other suitable moldable material is heated to atemperature at which it becomes plastic, thereby enabling it to beshaped manually to conform roughly to and overlie the die 18. While thematerial is still plastic, the mold half 20 is placed over the mold half15 with the die 18 and the plastic material thereon in registration withthe cavity 23. Thereafter, the mold is subjected to pressure of betweenabout 2500 and 3000 p.s.i.

The quantity of plastic material used in the molding process is morethan enough to fill completely the space between the confrontingsurfaces of the die 18 and the cavity 23. Accordingly, when the mold issubjected to pressure, the plastic material will be capable of flowingto all parts of the mold cavity and completely fill the latter.Sufficient space is provided between the stone material of theconfronting mold halves to enable excess material to escape the cavityas flash. Following the application of pressure, the molded part ispermitted to cool, after which the mold halves are separated and therough molded part removed and trimmed to form the finished pattern.

The production of a pattern by means of the disclosed molding techniqueis so simple that a relatively unskilled person may make a large numberof patterns per day.

The finished pattern 1 may be used by a dentist, dental assistant, ordental technician to produce an occlusal splint. As shown in FIG. 2, thefirst step in the procedure is to heat the pattern so that it becomessufficient pliable to be placed in a patient's mouth or between themaxillary and mandibular jaw models in an articulator and shaped asnecessary to conform to the patient's bite. In placing the pattern inthe patient's mouth or between the jaw models, the ridge 12 should belocated at the midline of the jaw. This will ensure proper orientationof the pattern even though the width of the base 6 is greater than thatof the patient's teeth.

If the splint to be formed is a maxillary splint, the pattern should beapplied to the maxillary jaw; if the splint to be formed is a mandibularsplint, the pattern should be applied to the mandibular jaw. Followingapplication of the pattern to the patient's mouth or model, and whilethe material of the pattern is still formable, the maxillary andmandibular jaws are moved toward one another to obtain an occlusion. Thepattern then is placed in an investment mold and invested, followingwhich it is removed and replaced by acrylic material which is cast,cured, and then polished to form the finished splint.

The pattern 1 disclosed herein is one for the production of a maxillarysplint. Accordingly, the high points of the protrusions 11 for formingthe cuspid risers are substantially coplanar with the surface of thelabial side wall. However, if a mandibular splint is to be formed, thecavity in the confronting mold surfaces may be reconfigured to providein the pattern protrusions like protrusions 11 but located substantiallycoplanar with the surface of the buccal wall. The cavity of the moldalso will be shaped to provide a depression like the depression 27 toproduce a ridge like the ridge 12 at the midpoint of the bight of themandibular pattern.

Since the pattern illustrated in the drawings is a maxillary pattern,the inner wall 9 is higher than the outer wall 8 so as to lie closelyagainst that part of the patient's palate adjacent the teeth and providestability for the pattern while it is in the patient's mouth or thearticulator. The pliability of the material from which the pattern isformed ensures proper fitting of the pattern to the mouth orarticulator.

It will be understood that patterns like those described above need notbe produced by the manual molding techniques disclosed. It is possibleto form patterns using single- or multi-cavity injection or vacuummolding techniques.

The disclosed embodiments are representative of presently preferredforms of methods and apparatus according to the invention, but areintended to be illustrative rather than definitive thereof. Theinvention is defined in the claims.

What is claimed is:
 1. A preformed pattern for use in the production ofa dental splint, said pattern comprising a generally U-shaped troughmember formed of material that is form-stable at room temperature butflowable at elevated temperatures, said member having a pair of limbsconverging in a direction toward one end of said member and being joinedto one another by an arcuate bight, said member having a relatively flatbase from one side of which spaced apart inner and outer side wallsextend in the same direction, the opposite side of said member having asurface that is substantially flat except for a pair of upstandingprotrusions spaced from one another along the arc of said bight, each ofsaid protrusions having its maximum height at a point substantiallyco-planar with one of said side walls and declining smoothly from saidpoint toward said surface.
 2. A pattern according to claim 1 whereinsaid inner and outer side walls are of different height.
 3. A patternaccording to claim 2 wherein said inner side wall is the higher of saidwalls.
 4. A pattern according to claim 1 wherein said inner side wallforms with said base an obtuse included angle.
 5. A pattern according toclaim 4 wherein said angle is substantially 110°-130°.
 6. A patternaccording to claim 1 wherein said outer side wall has an outwardprojection at substantially the midpoint of said bight.
 7. A patternaccording to claim 6 wherein said projection extends substantially thefull height of said outer side wall.
 8. A pattern according to claim 1wherein the material from which said member is formed is sufficientlyflowable when heated a few degrees above normal human body temperatureto enable an occlusion to be formed in said limbs.
 9. A patternaccording to claim 8 wherein said material is dental wax.
 10. A patternaccording to claim 1 wherein said base has a width greater than that ofa person's teeth.